Limnocharis flava, a species native to tropical America, is naturalized as a noxious weed in Sri Lanka, India and some other Southeast Asian countries. It is widespread in flood plains, wetlands and agricultural wetlands resulting in poor drainage. In the current study, the influence of different water conditions on growth, development and morphology of L. flava was investigated. Plants were grown on experimental pots filled with wetland soil, simulating flood, standing water and dry conditions. The highest biomass and relative growth rate was observed in the plants grown at flood conditions, while the lowest total biomass content was observed in the plants grown at dry conditions. L. flava showed morphological adaptations in different water conditions, including significant differences in the relative biomass allocation for root, petioles and leaves. Root biomass significantly increased in flooded conditions. Observed decrease in leaf area and increase in leaf total chlorophyll content may facilitate the survival in dry conditions. Plant mortality and no production of inflorescence may indicate the difficulty in surviving at dry conditions. No significant difference was observed between the plants grown under ‘high flood’ conditions and ‘low flood’ conditions. Overall, L. flava showed difficulties to grow under dry conditions, but performed well under other conditions.